1. Statement of the Technical Field
The inventive arrangements relate generally to transformers and more particularly to embedded toroidal transformers.
2. Description of the Related Art
Embedded toroidal transformers are known in the art. For example, U.S. Patent Application Publication No. 2005/0212642 to Pleskach discloses an embedded toroidal transformer in a ceramic substrate. The transformer includes a ceramic substrate comprised of a plurality of ceramic tape layers. At least a first one of the ceramic tape layers is layered between a plurality of second ceramic tape layers. The first ceramic tape layer can have a larger permeability value as compared to the second ceramic tape layers. In addition, one or more conductive coils are disposed within the plurality of ceramic tape layers. The conductive coil is of toroidal shape, having a central axis oriented transverse to the ceramic tape layers. Moreover, the conductive coil includes a plurality of turns about a region defining a ceramic toroidal core, wherein the ceramic toroidal core is intersected by the first ceramic tape layer.
Until now, only “step-down” and “one-to-one” toroidal transformers have been successfully embedded in a substrate. However, there are many applications where it is desirable to provide a “step-up” voltage response. In this regard, there have been various attempts at creating a functional step-up transformer. One problem with such embedded toroidal designs lies in that the magnetic flux induced by a primary input coil fails to effectively couple to the secondary output coils. This problem is largely due to the fact that induced magnetic flux in the secondary winding proves difficult to be constrained by metallic vias/traces. Therefore, what is needed is a novel embedded toroidal transformer design that can increase the voltage that is induced in a secondary winding. The novel design should achieve this by containing the magnetic flux that is formed in the secondary. At the same time, the step-up transformer design should not increase the x-y plane size of the toroidal footprint or require any additional machining or post processing steps.